The practical telephone handbook and guide to the telephonic exchange (1906)
Poole, Joseph · New York, Macmillan Co. · leaf 129
ittle current is pro-duced, both wires being at anearly equal potential, inwhich case the spark to otherconductors may give rise to afire. To guard against thisrisk, an easy sparking deviceis arranged, generally betweentwo blocks of carbon, the heat generated by the sparkingfusing a drop of fusible… … Fig. 103.—Scale £ SUB-STATION APPARATUS 107 Terminal Block.—To meet the requirements mentionedabove, the terminal block shown in Fig. 106 is used. Thiscombines a safety guard for each of the cases mentioned. The lightning arrester consists of two carbon blocks separ-ated by a piece of mica, of the…
Telephone
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